From the Old French name
Héloïse, which was probably from the Germanic name
Helewidis, composed of the elements
heil meaning "healthy, whole" and
wit meaning "wide". It is sometimes associated with the Greek word
ἥλιος (helios) meaning "sun" or the name
Louise, though there is no etymological connection. This name was borne by the 12th-century French scholar and philosopher Héloïse. Secretly marrying the theologian Peter Abelard at a young age, she became a nun (and eventually an abbess) after Abelard was violently castrated by order of her uncle Fulbert.
There was a medieval English form of this name, Helewis, though it died out after the 13th century. In the 19th century it was revived in the English-speaking world in the form Eloise.